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    利用宏基因组技术揭示土壤中的耐药基因组

    2014-06-28 16:17:19 南京迪康金诺生物技术有限公司 阅读

    抗生素抗性基因会轻易在医院环境中不相关的细菌之间转移,这促使人们猜测:土壤中抗性基因显著的多样性有助于抗生素抗性从环境生物向致病生物不断增加的流动。

    华盛顿大学医学院的科学家们解析了土壤细菌的耐药基因组(resistome),科学家们就一系列来自明尼苏达州和密歇根州的 18 个农牧业土壤样本对18种抗生素的抵抗力进行了功能元基因组筛选。研究人员发现,土壤中的抗生素抗性基因与特定细菌种属捆绑在一起,这说明种属之间的抗性基因传递很少发生。而在感染性的细菌中,抗性基因的共享要频繁得多。

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    原文检索:Kevin J. Forsberg, Sanket Patel, Molly K. Gibson, Christian L. Lauber, Rob Knight, Noah Fierer, Gautam Dantas. Bacterial phylogeny structures soil resistomes across habitats. Nature, 21 May 2014; doi:10.1038/nature13377

         Ancient and diverse antibiotic resistance genes (ARGs) have previously been identified from soil, including genes identical to those in human pathogens. Despite the apparent overlap between soil and clinical resistomes, factors influencing ARG composition in soil and their movement between genomes and habitats remain largely unknown. General metagenome functions often correlate with the underlying structure of bacterial communities. However, ARGs are proposed to be highly mobile, prompting speculation that resistomes may not correlate with phylogenetic signatures or ecological divisions. To investigate these relationships, we performed functional metagenomic selections for resistance to 18 antibiotics from 18 agricultural and grassland soils. The 2,895 ARGs we discovered were mostly new, and represent all major resistance mechanisms.We demonstrate that distinct soil types harbour distinct resistomes, and that the addition of nitrogen fertilizer strongly influenced soil ARG content. Resistome composition also correlated with microbial phylogenetic and taxonomic structure, both across and within soil types. Consistent with this strong correlation, mobility elements (genes responsible for horizontal gene transfer between bacteria such as transposases and integrases) syntenic with ARGs were rare in soil by comparison with sequenced pathogens, suggesting that ARGs may not transfer between soil bacteria as readily as is observed between human pathogens. Together, our results indicate that bacterial community composition is the primary determinant of soil ARG content, challenging previous hypotheses that horizontal gene transfer effectively decouples resistomes from phylogeny.
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